Akaka, 82, was first elected to the Senate in 1990, after serving 14 years in the House. He is the fifth-oldest senator, serving alongside Hawaii Sen. Daniel Inouye, who is the chamber's fourth-oldest member.

Akaka voted against the Iraq war resolution in 2002, and, in June, he was one of just 13 senators who voted for a measure sponsored by Sen. John Kerry, D-Mass., calling for U.S. troops to leave Iraq by July 2007.

By contrast, Case, 53, who was not in the House when the Iraq war resolution was passed, opposes setting a timetable for U.S. troops to leave.

Case, who has served alongside Akaka in the state's congressional delegation for the past four years, stunned Hawaii's political establishment in January when he announced that instead of running for re-election to his House seat, he would challenge Akaka in the Senate primary, on a platform of "change and transition."

Case represents Hawaii's 2nd District, which consists of Oahu outside of Honolulu and the rest of the state's islands. A former state legislator, he was elected to the House in a special election in 2002 to replace the late Rep. Patsy Mink.

The Democratic and GOP winners face each other in the November 7 general election to fill the seat being vacated by Case.